IC cards are classified into contact IC cards and contactless IC cards. While a contact IC card is physically connected with a card reader through its 8-pin terminal and communicates with the card reader, a contactless IC card communicates with the card reader using a radio frequency (RF) signal within a predetermined range.
The contact IC cards are employed in IC card terminals, various mobile devices, game machines, etc. embedded with subscriber identity modules (USIMs or SIMs), or security identity modules (SIMs). The contact IC cards do not include batteries, and are activated by power supplied from a power interface circuit only when connected to a card reader. When the connection is released, the supplied power is cut off, and the contact IC cards are kept inactivated.
To this end, a contact IC card reader has a card power interface circuit that supplies a voltage of a predetermined level when the contact IC card reader is connected with a contact IC card, and cuts off power supply when the connection is released.
A power interface circuit of a conventional contact IC card reader is implemented by a one-chip interface device, which cannot stably maintain the voltage of a power output terminal at a zero level even when separated from a contact IC card. Sometimes, the voltage of a power output terminal is maintained at a predetermined level (about 1 V) or above and affects the contact IC card.
Also, the power interface circuit of the conventional contact IC card reader occupies a large space due to a characteristic of the circuit configuration, and thus it is difficult to reduce the size and production cost.